Bevel is warping the surface
For the moment you can't bevel the edge because you have an inner face, the edge is common to 3 faces and therefore Blender can't guess how to bevel, once the inner face deleted, Ctrl B should work:

If you have a problem of shortcut, you can open the Preferences &gt; Keymap and type &quot;bevel&quot; in the search field, then redefine the shortcuts you want for this operation.